The conventional manufacturers of a semiconductor product are roughly divided into a wafer maker which manufactures a semiconductor wafer to be used as a substrate, and a device maker which forms various devices such as a memory on this wafer.
A wafer maker receives a product specification from a device maker, pulls a single crystal ingot according to the specification, slices the single crystal ingot, and conducts wafer processing in which at least one main surface is subjected to mirror polishing, other heat treatments, or the like, to produce semiconductor wafers, and then supplies (sells) them to the device maker.
The device maker forms a device on the wafer supplied by (purchased from) the wafer maker using an aligner such as a stepper, and manufactures and sells semiconductor products such as a DRAM and a flash memory.
A general specifications ordered by a device maker to a wafer maker comprises, for example, quantity, time of delivery, properties of an ingot and a wafer (a diameter of a wafer, a conductivity type, resistivity, oxygen concentration, flatness), or the like.
In the present circumstance, a wafer is manufactured and supplied by a wafer maker according to a specification required by a device maker. Even if it is suited to the required specification (even if it is within a standard), a problem that a yield or the like gets worse has occurred in a device maker.
The reason thereof is considered to be that with a tendency to high integration of a device or the like, a margin of a process has been decreased and a wafer quality higher than the required specification is sometimes demanded, and the quality which is not in the specification may have influence.
Conventionally, it can be evaluated whether a wafer produced based on the required specification in the present circumstance has sufficient compatibility to an apparatus or not by this. If the compatibility is bad, the wafer is evaluated to be bad. Even if the wafer maker improves a generally required specification such as flatness, it has been tended to be bad.
Then, the wafer maker itself has devised the wafer manufacturing process, and has matched it for each device maker. For this reason, wafer production lines (conditions for manufacturing a wafer) of various processes have been made.
Moreover, problems such as a yield may also be caused by difference in the production line on the side of a device maker, especially by variation of characteristics of apparatus to be used, or the like.
Therefore, even though the wafer is matched on the wafer maker's side, matching may become worse when the device manufacturing process on the side of the device maker, especially the apparatus to be used or the like is changed. As described above, a really desirable wafer has not been supplied only with response on the side of a device maker.
Accordingly, it has become difficult to supply a wafer stably, unless a wafer maker manufactures a wafer with considering manufacture conditions or the like on the side of a device maker. Moreover, it has become also necessary for a wafer maker to respond quickly to a change of a device manufacturing process in the device maker.